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    Sol-20 with FDC+ BOOTing to CP/M ???

    I created bootable disk images running CP/M 2.2 on a Sol-20 computer with the Altair FDC. See the link below. The directory and data tracks of theses disks are compatible with all Altair CP/M disks. https://deramp.com/downloads/processor_technology/sol-20/software/altair_fdc/disk_images/ Mike D
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    Sol-20 with FDC+ BOOTing to CP/M ???

    I'll create one over the 4th of July holiday weekend if I have the time. Mike D
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    Poly-88 Schematics Request

    The best versions I have are here: https://deramp.com/downloads/polymorphic/ I have numerous “original” sets of schematics and assembly drawings provided with Poly-8813 systems and they’re all copies of copies, so even the original printed material was often poor. Mike D
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    ELIZA pre-AI software from Microware

    I pulled out my SWTPC 6800 and loaded the S-Record file Ben created. It plays pretty much the same as the typical BASIC version. Unfortunately, the audio volume is still to low to load using a working SWTPC cassette interface or a working KCS cassette board in an S-100 machine. Thanks for...
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    ELIZA pre-AI software from Microware

    I'm not able to get anything but garbage out with an SWPTC cassette interface or with an S-100 KCS cassette board (both working). How did you record the audio - it almost sounds like it's picked up with a microphone in a room. Mike D
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    Shugart 850 and Cromemco 16FDC

    The same circuit is used for reading both the bottom head and top head of the drive. The same applies to the write circuit. Since top and bottom work in SD and the bottom works in DD, it’s most likely not the electronics. I’d clean the heads with a q-tip and alcohol if you haven’t already...
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    Altair ROM BASIC

    Martin Eberhard dumped the ROMs from two of these boards that he has: an 88-RBM and an 88-RBM II. The ROMs on the two boards had similar date codes. The content of both sets of ROMs was identical and the Altair banner and copyright were suppressed in both sets. We surmise that Pertec themselves...
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    Altair ROM BASIC

    I just realized today that the only copy I've ever seen of the ROMs from the Altair 88-RBM board have at least one modification versus the original ROMs. Does anyone still have this board that could dump the ROMs for me? I want to see what other differences - if any - there may be. The...
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    Intel hex to .ent utility for Sol-20

    Based on testing a Model 28 Teletype I'm working on, I just figured out that TeraTerm does not send the LF of a CR/LF ending if the binary option in the "File->Send File..." dialog box is unchecked. This means you can send existing .ent files without having to modify the file to strip LFs if...
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    Intel hex to .ent utility for Sol-20

    I imagine I've re-invented the wheel, but I created a utility to convert Intel hex files to .ent files for the Sol-20. The utility writes each line with just a CR at the end (no LF) so you can transmit .ent files to the Sol-20 at 9600 baud using a 100ms delay per line setting in your terminal...
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    Flyback Transformer for Panasonic 9” B/W Monitor

    Does anyone happen to have a TLF4C60801M flyback transformer for a Panasonic 9” monitor? Or know an acceptable substitute? This is for a Panasonic WV-BM900 monitor. I’ve got a hit from Sears, but that’s about it. Nothing on eBay presently. Mike D
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    ICOM FDOS-III for the Poly88

    Today, I did a bit more work on disassembly of those sections of EXEC involved in disk I/O. It expects several functions not present in the PROM shown in the manual, and some of the functions it expects change/overlay existing jump vectors to do something else. Maybe they were trying to make...
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    ICOM FDOS-III for the Poly88

    Interestingly, the native format of executable files in FDOS actually is Intel hex, but I haven’t gotten to the point of loading files from disk. I let the PROM go through its boot initialization of hardware and data, then I manually load EXEC into memory (that’s what the boot process does)...
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    ICOM FDOS-III for the Poly88

    OK, that’s an important answer. As I mentioned, the FDOS-III manual says the support PROM is at C000 (for the Poly-88) and the support PROM listing in the FDOS-III manual matches the PROM I have. That PROM listing, in turn, says it’s for “8080 Altair/IMSAI/Poly 88 FDOS III Version 1.0”...
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    ICOM FDOS-III for the Poly88

    Did the disk label show “FDOS-III” or just “FDOS?” Did you see anything in the content that might indicate FDOS-III in particular? Mike D
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    ICOM FDOS-III for the Poly88

    Lol, since a tantalum cap failure is either explosively obvious, or a highly common short (especially on the higher voltage supplies), I’d say you’re “experienced”, not “psycho” :)
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    ICOM FDOS-III for the Poly88

    Yep, it’s almost always a tantalum. This time it was a “silent” tantalum failure/short on the CPU board without an explosion. The first sign of a problem I noticed was smoke from the power supply. Three diodes have failed including the little 1N4148. I’m just going to replace all seven diodes...
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    ICOM FDOS-III for the Poly88

    I have the FDOS support PROM source recreated and can now reassemble the PROM at B800 as required for the Poly-88 FDOS files found on this disk. I pulled out my Poly-88 and used it for a while this morning to make sure everything was working fine, but unfortunately, after about 15 minutes of...
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    ICOM FDOS-III for the Poly88

    Looking at an automated disassembly of this EXEC file, I can see it is expecting the Poly-88 version 4 monitor, and since the files all load at 2100H, this too fits with the Poly-88 (ROM in low memory space). Oddly, this EXEC expects the FD3712 interface card to be at B800 instead of C000. The...
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    ICOM FDOS-III for the Poly88

    Ok, that makes more sense - it’s an archive of binaries for FDOS-III saved in Intel hex format on an ISIS disk. The EPROM on the interface board provided with the FD-360 and 3712 does most of the disk and console I/O, so it still may be possible to get a bootable disk working by loading EXEC...
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