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I would like to get the RTC going in my Model III which came as a feature on the aftermarket Holmes FDC DX-3D board it has fitted. I renewed the on-board battery, but first relocated it to make future renewals easy. I can't find any docs about this FDC + RTC, so have tried Newclock-80 port...

In the day, was there a popular & practical add-on that gave a cassette-based Model 1 the RS-232 function without buying an Expansion Unit? Thanks Philip

In 1988/9 I worked for a small software house programming Wang 2200 MVP's. Our typical clients were small businesses that used their 4-6 terminal systems for inventory control, payroll, debtors/creditors, etc. I left the industry in 1989 and now wonder what would have been a good migration path...

I'm about to take delivery of a Toshiba T2100 (8086, gas plasma) but have failed to find any documentation for this model on the net. I'm particularly interested in the maintenance manual, but other manuals would be good too. What doesn't help is that this model was apparently only marketed in...

Hello all I'm fitting CP/M up to an 8085 system that uses a RAM disk as opposed to floppy disks. I'm stuck with figuring out the Disk Parameter Block I should be using, the Alteration Guide just isn't making sense to me. What I have is: 8 sectors (0..7) of 128 bytes (1024 bytes) 256 tracks...

Hi all I wish to know how interrupts are handled, if at all, under CP/M on an 8080. On this system which I'm implementing CP/M, keyboard scanning is done on the Int 7.5, so a return address can be plonked on the stack at anytime. Now with the scenario of a user program using the stack & SP in...

I can't get DSK/DCT to work, on my Model 4. Following the article in TRS8BIT June 2015, I enter the SYSTEM command as instructed. I get as far as the "Enter image filename:" prompt where I enter CDISK1.DSK. Here grief happens... with the response "Failed!". CDISK1.DSK is on my SD card, VHDUTL...

I've just completed an 8080 emulator to run on my TRS-80 Model III. My aim was to experience what's involved in emulation & I had a goal that it should run Altair 4K Basic in high memory. It now does this, but I quickly discovered a problem with the floating point - it looks like a rounding...

In my search for a schematic for Tezza's monitors, I had a "bingo" moment. Frenetic googling revealed the chassis number "TCF-12" is shared with a Tote-Vision TV of the 1980's. The era & country of origin matches these monitors. However additional searching didn't find the relevant Tote-Vision...

I've just read Paul Allen's book Idea Man and have a few general questions about his 8080 emulation on a PDP-10. I have no experience with PDP-10. Timeshare crash: We all know assembly language development can often produce a crash. On a PDP-10 would this crash the entire system (all users on...

I struggled with the heading for this post. I want to investigate using a Z80-based microcomputer (say a Kaypro II or TRS-80 Model I-IV) to diagnose another (faulty) Z80-based system. I envisage unplugging the CPU of the faulty system and plugging in a header cable & performing RAM/ROM checks...

I've recently acquired a Pocket Computer PC-2 (quite rare here in New Zealand) that has the 8K RAM module (cat 26-3616) installed. However when I do a MEM or STATUS 0, I still get 1850. I've done a cold reset, and removed & cleaned connectors on RAM module - no change. I have searched for the...

Greetings all I thought I'd give my Kaypro II a 'heat soak' test while I waited for another keyboard/parts. All went well for about 5 hours, then the screen showed wierd characters. On re-boot, the screen just fills with wierd characters, many of them flashing. It obviously doesn't get very...

Greetings all Those following Tezza's Kaypro keyboard fault may remember Well, that machine is now mine. I have only a small collection - TRS-80 Model III & a few TRS-80 Model 100's. However I want to pursue an interest with CP/M and a Kaypro should do this nicely. Buying it was quick -...

After checking out Tezza's Kaypro II in the flesh, I thought 'what would it take to get one of these things?' :D A quick check on eBay revealed a nice looking Kaypro (auction number 300039229895 ) But oh, the Buy Now price = $US 35,000 :shocked: It looks like I'll have to save up to buy that...