Recent content by retrogear

adjust the horizontal hold VR4005 to get the bars running vertical instead of diagonal. If they don't lock but just float across then you are missing horizontal sync. The manual shows where video comes into pin 1 of IC4002 then thru a sync separator. See waveform 3 on pin 1. That is 4.8v of sync...

There are several possibilities including a short on the grid or cathode of the tube (hopefully not) but the more common is the loss of the cathode bias voltage which is typically derived from the flyback via a winding on it's secondary with a diode and capacitor. The voltage is about 200VDC...

That photo was using composite which is B/W only. I have used a level converter board plugged into CGA out then wired into a GBS8200 scan converter to VGA to get decent color. The Z100 had a GIF decoder program. This is my best color ever with an NEC display.

I know. It also was graciously given to me by another individual in this group a decade ago. It has an NEC FD1165. I can unplug it and plug into my MS-DOS machine to image 8" disks with IMD or do files with 22DISK. I see silcreval you already have the Winchester version. I use Z-DOS v2.13 most...

It's a fun machine. I added a Seagate ST-225 hard drive and an 8" floppy drive to mine. The floppy card has a 50 pin header for it. My rom is v2.5 which I think you need to run a hard drive but you also need a ST-506 card with a piggyback data separator which is a holy grail to find anymore...

circled in yellow

the cap Andy referenced is C423 near the flyback which is also a likely area for breaking a trace

there are bios calls for set source/destination banks then another call for block move. There is a call for select bank for code execution and another for set bank for disk i/o and dma. This is fresh in my mind because right now I am disassembling a cpm+ bios. Cpm+ has a BDOS API to call bios...

If you repeatedly tap the F2 key after power on you can't get to the bios ?

I had a report of a bad 74LS02 at B13. That creates the timing window for color burst. No burst = no color. Larry G

Looking thru the UTS-30 manual that gives the files released on the disk for CP/M Plus Release 1R1 contained no SPR files, only CPM3.SYS already configured.

<It sounds as if you're having to rebuild the BDOS so the resbdos$pg ends up as the address the BDOS will actually be loaded at, rather than with the magic values that get altered by GENCPM. In which case the difference in resbdos$pg will> <be the difference between the load addresses of the...

I was able to reverse engineer the banked bios to make the required BIOS3.SPR and BNKBIOS3.SPR and get GENCPM to create CPM3.SYS. I turned on the SPR report display as well but to make this work I also had to reassemble RESBDOS3.ASM and BNKBDOS3.ASM to get things to line up. I had to use...

you could try unplugging the internal degauss coil then do a manual degauss with your ring. leakage current thru the internal coil could create a pattern like you're seeing Larry G

I am creating a single BNKBIOS3.SPR with this: link bnkbios3(b) = bnkbios3,scb,bios3 I have set bnkbios3.asm to dseg and bios3.asm to cseg What would be the process to load cpm3.sys into memory then save it as a consecutively addressed bin file ? I would think somehow create and run a...