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SOFTWARE THAT I USE FOR HELL
Since ca. 1980, a number of software emulators for "Streifenschreiber" (paper tape printer) Hellschreibers have been developed for home computers such as PC (DOS, Windows®, LINUX), Apple/Macintosh, Commodore, Olivetti, and ACORN.
In 1983 I bought a CHE-1, a cloned-and-improved Apple-II, developed by Computer Hobbyclub Eindhoven. The first Hell-software that I used ran on this machine (yes, loaded from a cassette recorder). It was developed by Klaas Robers, PA0KLS, and described by Klaas in "Micro-hell", Electron, 7/1980 [in Dutch; English translation provided by Andrew, SM6MOJ]. It was a whopping 2 kB in size (written in assembler and/or machine language)! This Hell-software can be downloaded here (Apple .dsk file that also includes RTTY and SSTV). The screenshots below, and those of the instructions & explanations included as part of the program are here.
I was able to run this software under Windows® XP with the Apple II OASIS emulator. The program executes fine with this emulator, but it uses the Apple's 16-pin DIP Game Port socket (ref. 21, 22) to interface with a transceiver:
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pin 2: "pushbutton 0" (SW0) = audio in ("signal present") |
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pin 14: "Annunciator output 1" (AN1) = PTT |
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pin 15: "Annunciator output 0" (AN0) = TX key-down for direct keying of a CW transmitter |
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pin 8: ground. |
These are TTL-level input and output interfaces (74LSxxx series). OASIS uses the joystick-driver of the PC (inputs only). My laptop doesn't have a game port, but I do happen to have a Gameport-USB adapter (Radio Shack item 26-164; they no longer sells this item). Pushing one of the buttons on an old joystick, I can invert the received signal on the receiver screen. Will try and hook up audio one of these days. Note that only Aplle II, II Plus, and IIe have the 16-pin game connector. Apple IIc does not support the required ANx outputs.
Screen-captures of the PAØKLS
Hellschreiber emulator (running on OASIS)
At the university, I was still using my "personal" DEC PDP-11/23 at he time! A couple of years later I got an old PC, and found the Hell-software for MS-DOS by Sigfus Jonsson, LA0BX. It can be downloaded here.
The DOS-Command function available as part of Windows® (Win95 and beyond) actually is a severely limited DOS-emulator, and it will not provide the required access to the LPTx or COM port, even though it may execute the HS.exe program. I installed an excellent DOS x86-emulator (DOSBox, freeware). It is geared towards DOS-games. The version I have (V0.73, May 2009) unfortunately doesn't support LPT ports yet (the serial COM-port supposedly works). The LA0BX software requires a simple HamCom-type interface as described further below. Like the above Apple II program, the RX/TX interface is at TTL-level, rather than using a sound-card (though if you crank up the audio output of your RX, you may get these Hell-printers to work without an additional interface).
Screen-captures of the LAØBX
Hellschreiber emulator
In those early days of home computing (1980s), Hellschreiber software was also developed for the Z80 (e.g., PA3CTL), ACORN (e.g., Marien, PA0MVW), Olivetti M10 / Tandy 100 (e.g., Hans, DL1AN), and Commodore C64 (Louis, PE1DXH/PA3DSA; C64 emulator for Windows® e.g., CCS64).
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"Feld-Hell mit dem Olivetti M-10", Hans Kreuzer (DL1AN), cq-DL, 1988, nr. 3, pp. 162-163 |
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"Hellschreiben mit Commodore 64/128", CQ-DL, 1989, p. 525 |
Note that the above Hell-emulators by PAØKLS, LAØBX, and PE1DXH are still the only (non-commercial) ones that include the 72 "GL" start-stop Hellschreiber mode.
Currently I have several Hellschreiber and Hell-capable multi-mode software programs for Windows® on my laptop. They all use the PC's sound card. I actually use an "Audigy® 2 ZS Notebook" PCMCIA sound-card, rather than the built-in card. It is accurate enough to not need a calibration offset. It also supports 96 kHz sampling and has a stereo-input, which is what I need for my SDR project.
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Hellschreiber - freeware from Nino, IZ8BLY, co-developed with Murray Greenman, ZL1BPU. |
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MultiPSK - multi-mode freeware from Patrick, F6CTE (includes Hell-80 synchronous mode and Hell-80 "start-stop" transmission, and has slant correction buttons during receive). |
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Fldigi - ("Fast Light Digi-mode") freeware by David, W1HKJ (includes Hell-80 synchronous mode). The Fldigi website is here. A description in German of this software is "FLDigi - ein Multi-Digimode-Programm" (Eike Barthels (DM3ML), FA 5/09, pp. 510-513). |
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Digital Modes 780 (DM780) - very nice multi-mode freeware from Simon, HB9DRV, et al; it has a freeware counterpart (Ham Radio Deluxe, HRD) for the PC-control program of CAT-capable transceivers an some SDRs. The Hellschreiber functionality of DM780 is ported from Fldigi (except for Hell-80). |
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MixW good multi-mode pay-ware (about $50) by Nick, UT2UZ, and Denis, UU9JDR. |
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WinHell by Henk, PA3BQS. This freeware allows the user to define the detector characteristics (curve of signal level vs. pixel brightness). As shown in the screen capture below, this also allows selection of inverse video (white-on-black) which is helpful under noise/interference conditions. It is the only software that includes a character-matrix editor. There is also a beta-version with sliders for the center frequency and bandwidth of the detector. |
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SkySweep was multi-mode pay-ware, discontinued in 2009. It has many configurable signal processing functions, but a rather awkward GUI. It covers Feld-Hell, PSK-HELL-105 and -245. |
Screen-captures of the IZ8BLY
(left) and DM780 (right) Hellschreiber emulator
(click
on image to enlarge)
Screen-captures of
the MixW (left) and Multipsk (right) Hellschreiber emulator
(click on image to enlarge)
Screen-captures of
the Fldigi (left) and WinHell (right) Hellschreiber emulator
(clock on image to enlarge)
Screen-captures of SkySweep Pro 5.11 in Feld-Hell mode
(click on image to enlarge)
Hell-80 machines can operate in synchronous mode (like the Feld-Hell), and in asynchronous (start-stop) mode like the Hell 72 "GL" and 73 "AGL" machines). The available Hell-80 capable emulators all do the synchronous mode. Only MultiPSK can transmit in the asynchronous mode (i.e., "start-stop"). However, all can receive start-stop transmissions. In this case, the start-pulse in the first column of each character will simply be printed, rather than be used for synchronization.
Company/corporate PCs and laptops typically do not allow you to install software (no administrator rights). No problem! Just install your software on a USB memory stick. I have done this with the IZ8BLY software in about 2 minutes. Download the software package and start the installation software (setup.exe). Do not install the software to the default location (C:\Program Files\Hellschreiber) but use the "browse" button to locate the USB stick. Then install there. Once the installation is done, stick the US stick into the company PC and run the application (IZ8BLY Hellschreiber.exe) from there.
More exhaustive lists of various Hellschreiber emulator programs can be found here (DXzone), here (Ko, NL9222), here (Murray, ZL1BPU), here (Oliver, DL9QJ), here (Andrew, SM6MOJ), here (BUXCOMM), and here (Craig, KF4HOU). The multi-mode Mac programs cocoaModem (by W7AY) and Multimode (by N3JLY) also do Hellschreiber; cocoaModem is the only emulator with "position" buttons for realigning the text lines vertically (to get two fully visible parallel text lines).
I primarily use the IZ8BLY software. Maybe simply out of habit. For some reason I tend to revert to dedicated software, like I do for SSTV (MMSSTV) and RTTY (MMTTY). Sometimes I run MixW or DM780 in parallel (I do prefer audio spectrum and waterfall displays in color). Here are a couple receiver screen-captures of QSOs with IZ8BLY software.
The IZ8BLY can automatically save a capture of the receiver-screen every 2 minutes or so. I use this feature for my Hellschreiber WebCam. IZ8BLY does not include an ftp feature to automatically upload the screenshots to my website. DM780 does include such a feature, but only for SSTV... I use FTPGetter for automatic uploading of screenshots and WebCam status. FTPgetter is shareware, not freeware; I still use the full-capability demo version that now has an increasing wait-time before it enables its functionality - no problem. My FTPgetter settings (with the exception of the password, hi) are here.
Click here for a write-up by GØHWC on how to calibrate the TX/RX clock settings of some of the above software packages.
If you'd like to more closely analyze the spectrum of the audio signals you receive, consider "Spectrum Lab" freeware from DL4YHF. You can also use this to look at the spectrum of the audio signal that the digi-mode software sends to your transmitter. I have put the spectrum plot of a various Hell-modes on the "Modern "software" modes (FM, MT, etc.)" page.
You can test your software and receiver-PC interface (see below) with these Hellschreiber recordings. (or you can install multiple Hellschreiber softwares and have them "talk" to each other on your PC). These and other digi-modes recordings can be found on my sound-clips page. These days, I use ScanRec freeware to record digi-modes receiver audio (settings: PCM, 8 kHz sampling, 16 bit, mono).
The above software packages can
also be used to test Hellschreiber machines. However, none cover
all mechanical Hell modes, in particular Hell "F" (same signal format as "Presse
Hell"), synchronous Hell-80, and NVA (ATF) Hell. Ralf Lampe
has solved this shortcoming with his EREL-Hell software. Early 2011, he added
the NVA (ATF) Hell mode as part of V1.23. It can be directly downloaded
here, from his EREL
Telefonsammlung
website. Note that this software is explicitly designed for testing Hell
machines. The generated tone-pulses are not suitable for modulating a
transmitter.
GUI of the EREL-Hell test signal generator
SOUNDCARD INTERFACE SCHEMES
Obviously the PC needs to be interfaced with a transmitter/receiver. Typically the following interfaces are required:
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audio from the receiver loudspeaker, headphone, or line output to the microphone ("mic") or line-in of the PC's soundcard |
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audio from the soundcard to the mic input of the transmitter |
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PTT-control from the serial port of the PC to key the PTT-input of the transmitter. You may be able to use VOX instead:
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Note: the modern Hellschreiber software discussed above, do not support direct keying of a CW transmitter! Only the old DOS-based and Apple II Hellschreiber software supports direct keying! The only option is to use a keying circuit between the audio output of the PC's soundcard, and the keying input of the CW rig. The keying-circuit recovers the original binary (DC) pulses, by rectifying and filtering the tone pulses. The recovered pulses are passed to a keying tube (or transistor), the output of which is connected to the keying input of a CW transmitter.
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The Hell Co. designed tube-based keying devices to do exactly that (1940). See figure 14 in ref. 14. |
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For use with a solid-state CW transmitter, a keying circuit can be made by expanding a CW/Hell demodulator (ref. 15, 16a, 16b) with a keying transistor. |
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Likewise, VOX circuitry can be used, e.g. one of the circuits by G4JNT (ref. 17) |
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A keying circuit can be as simple as a diode rectifier, an RC-filter, and a switching transistor. Two diodes and two capacitors can be configured as a full-wave voltage doubler, that consists of two half-wave rectifiers operating on alternating polarities (ref. 18). |
Originally I used the HAMCOM-style interface by Sigfus, LAØBX (see "PC Hell", in Norwegian with appended English translation by Andrew, SM6MOJ). The PC board for this interface was kindly provided to me by Helmut, DL1OY, in September of 1992 . The circuit design is by Kåre, LA9ZO.
LA9ZO Hell PC-interface (HamComm-type)
(top left: I added a
transistor for PTT-interface)
Click here for a description of how I hook up my laptop to my transceiver these days. References 1 through 13 provide some more interface descriptions and designs:
To prolong the life of your PC etc., the PC and the transceiver must be galvanically isolated from each other - especially if you have a transistorized transceiver. This can be done with small isolation transformers for the audio, and opto-couplers for the PTT interface. It is highly recommended to install the audio isolation even when just using a receiver. If you have a modern transceiver, make sure that the speech-processor is "off".
I have had some problems with RF into my PC, and have added ferrite rings (I normally use ferrite material 43 for chokes) and clamshell clamp-on ferrites to AC- and DC-power cables, all audio signal I/O lines, and USB cables (keyboard, hub, etc.). My cordless mouse also locked-up at some transmit frequencies, and I have reverted to a USB wired mouse. Note that the Logitech® cordless mouse operates at 27 MHz (per the Logitech website, some newer models run at 2.4 GHz, some at 100-145 kHz; other brands apparently use 13 MHz)...
Recent laptops and notebook PCs no longer come equipped with a serial COM-port. This means that the standard interface for the PTT signal is not available. USB-RSR232 adapters are available commercially. However, they do not include galvanic isolation (opto-coupler). A USB-RS232 converter chip is readily available: the FT232BM chip from FTDI Ltd. It works with all popular digi-mode software packages. If required at all, a driver for Windows etc. is readily available. This chip is also built into some inexpensive serial-USB dongles.
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Click here for the datasheet of the chip. |
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FTDI Ltd also sells various USB cables with the chip built into the USB connector. Check their on-line shop. All you need to add is an opto-coupler. |
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"Universelles USB-Interface für (fast) alle Fälle" by Michael Wöste (DL1DMW). Example of a simple converter circuit with galvanic isolation is here (includes a link to eShop for a bare circuit card); in German, but schematic is easy to interpret. |
The same considerations and precautions apply to Hell modulation as to fast CW, and PC-based digi-modes (ref. 20):
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Correct setting of the audio level of the PC's sound card line out put |
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Correct setting of the transceiver's microphone gain |
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Correct setting of the transceiver's power |
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Turning off the transmitter's speech processor |
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Turning off the transmitter's Automatic Level Control (ALC) to avoid clipping (non-linearity) |
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Avoid ground loops (when using a PC and digi-modes software) |
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Avoid picking up 50/60 Hz hum (when using a PC and digi-modes software). |
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Tune the transceiver's frequency, such that the audio frequency of interest is in the middle third of the waterfall spectrum display (typical transceivers have a receive and transmit bandpass of 700-2000 Hz, with rapid fall-off near these band edges) |
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See here for illustrations of the received spectrum of over-driven transmitter and broadband 50/60 Hz and 100/120 Hz artifacts. |
Articles:
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"The care and feeding of digital, pulse-shaping filters", by K. Gentile, RF Design, April 2002 |
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"The shape of bits to come", by James, G3RUH, version 29 October 2005 |
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"CW Envelope as a Function of Rise Time", by Greg, W8WWV, version 26 February 2003 |
My transceiver-PC
interface "spaghetti", ca. 2002
April 2009: I decided to replace the spaghetti interface with a commercial interface box: a Signalink SL-1+. It is about the size of a pack of cigarettes and does the job. Did have to reduce the microphone gain setting inside my transceiver, to be able to get Signalink's PTT function to work properly with the PC's Sound Mixer without over-driving the microphone input to the transmitter (this issue is covered by the Signalink instructions). Also had some issues with inadvertent PTT activation at certain combinations of audio source selection ("what you hear" vs microphone (from RX) and wave (from web-SDR)) and wave & overall volume setting in the PC audio mixer.
December 2009: I have decided to
revive my spaghetti interface! Reason: the Signalink Model SL-1+ (and similar
type interfaces) do not have input & output volume control potmeters [note
that this serious shortcoming has been corrected in the latest Signalink model].
For being able to quickly change gain settings, having potmeters is much
easier than having to activate and use a soundcard interface utility on a PC. I
have put the potmeters and circuitry (now including a PTT-LED) in a small
project box, and cleaned up the wiring mess.
February 2010: I have expanded the interface with a second output of the PTT-optocoupler. This allows me to direct-key a CW transmitter. The latest circuit diagram is here. A DPDT toggle switch is added to avoid simultaneous activation of the PTT and CW Key lines. Note: currently, only the old DOS and Apple based Hellschreiber software supports direct keying!
My latest transceiver-PC interface - 2009
REFERENCES
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Ref. 1: "Understanding Soundcard Interfacing" by Ernie Mills, WM2U (includes specifics for all sorts of transceivers, including classic tube transceivers that may have as much as -30 to +100 Vdc on the keying lines) |
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Ref. 2: "A basic guide to CAT and audio interfacing" by Peter, PH1PH, Basil, G4TIC, Simon, HB9DRV |
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Ref. 4: "PC RFI reduction and sound-card interface", by Dale, VK1DSH, WIA Amateur radio, July 2009, pp. 5-9 |
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Ref. 5: "Funkfernschreiben - Textübertragung auf Kurzwelle - Ein Streifzug durch die Welt der digitalen Betriebsarten", by Dieter, DL2RR (excellent overview of digi-modes (incl. Hell) and interfacing; in German) |
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Ref. 6: "A Flexible Digital-Mode Interface" by Jim, N9ART, QST, 11/2000 |
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Ref. 7: "Build your own PC interface" by Rahul, VU3WJM (reverse-engineered Rigblaster "Nomic") |
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Ref. 8: "The OPTO-IF A Digital Mode Interface Kit", by David, G3GFP |
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Ref. 9: "Getting started with sound card digital modes", by Murray, ZL1BPU (used with permission) |
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Ref. 10: "The Universal Keying Adapter" by Dale, N0XAS, 2008 ARRL Handbook for Radio Communications, pp. 19.22-19.24, plus N0XAS kit manual |
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Ref. 11: “Hellschreiber (J2C) con targeta de sonido”, Valentin Alonso (EA4CBH), Radioaficionados (revista de URE), no. 10, 1999, pp. 56-57 |
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Ref. 12: "Tosi2000: Universelles Modem für SSTV und Fax", Bernhard Thiem (DF5FJ); (interface kit description incl. schematic; also described in CQ-DL, 9/98, page 693) |
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Ref. 13: "Die Soundkarte im Amateurfunk", Reinhard Krause-Rehberg (DK5RK); also appeared in CQ-DL (Special Issue), 2002. |
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Ref. 14: section 9a and 9b in "Die Entwicklung des Hell-Schreibers" by the inventor himself: Rudolf Hell; pp. 2-11 in "Gerätentwicklungen aus den Jahren 1929-1939", Hell - Technische Mitteilungen der Firma Dr.-Ing. Rudolf Hell, Nr. 1, May 1940 [in German] |
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Ref. 15: "CW Demodulator" [a synchronous CW/Hell demodulator], Jan-Martin Nøding (LA8AK), Amatørradio 1987, February, Nr. 41, pp. 41-43, March, Nr. 42, pp. 66-69 |
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Ref. 16a: "Een CW-Hell interface", Klaas Robers, PAØKLS, Electron, 12/1980 |
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Ref. 16b: "Ein CW-Hell Interface", Helmut Liebich (DL1OY), RTTY - Informationsorgan d. DAFG e. V. u. d. Swiss-ARTG, Jg. 12, Nr. 1, January 1981, pp. 5-8 [translation of ref. 6a, with PCB layout added] |
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Ref. 17: "Audio VOX Circuits", Andy Talbot, G4JNT |
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Ref. 18: "CW Rig Keying Circuit for Hell", Mike Blake, K9JRI |
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Ref. 19: "A Flexible Digital Mode Interface: One interface, all the software", Jim Mitrenga (N9ART), HAM-MAG, Nr. 15, April 2010, pp. 10-15 |
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Ref. 20: "9 Tips for the PSK31Digital Mode", Dan, HAM-MAG, Nr. 15, April 2010, pp. 18-9 |
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Ref. 21: p. 100 in "Apple II Reference Manual", 1979, 209 pp., source: www.virtualapple.org |
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Ref. 22: p. 38, p. 184, 185 in "Apple II Reference Manual - For IIe only", 1982, 284 pp., source: www.virtualapple.org |
My station, all hooked up
