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Early this summer I got a version of this board up and running CP/M off of 8" disks. My board may predate yours in that it is marked WINTECH SYSTEMS which later became WIN SYSTEMS. The part numbers appear to be the same though. The EPROM label was missing but it holds a simple monitor; probably...

Recently I've had this happen with TEAC drives when using disks that do not have reinforcement rings. Once the collet decides to let go, the center hole appears to be stretched forming the slightest rolled edge of the holes periphery.

The dev_names char array is not a valid substitute for the device_name_o char pointer. The comment indicates what the type it should be so why not just declare it as char *dev_names. The DDT struct initialization can remain the same. The pointer is maybe 4 bytes and the char array is 32 bytes...

Might the DS1 and DS0 designators belong to the outlined resistors and not the oval pads. If this is the case the drive is strapped for DS1. If the "DS1" resistor measures 0 ohms then it's likely a jumper.

I do not think the resistor networks (RN1, RN2 and RN3) can be replaced with discreet (isolated) resistors the way you have them. A quick check of the BOM gives Mouser part numbers 652-4116R-2LF-4.7K and 652-4116R-2LF-10K. The Mouser part numbers map to 4116R-2-472LF and 4116R-2-103LF...

DB0 (data bus bit zero) is required. It also looks like IO is broken as it passes C9 and C11. Also the square GNDREF pad of C9 shows as rats nest (unconnected). Something does not look correct with power connectors P1 and P2. On the PC motherboard the grounds of P1 and P2 are next to each...

Congratulations on getting these up and running. The layout planning and craftsmanship make them works of art.

The Tava ROM image runs fine when loaded it into an EPROM emulator at U87. As a quick crosscheck I get following crc32 and sha1sum on the unzipped ROM: crc32 - 5aeb1b17 sha1sum - 2278c5b278aa1e0e764e7cd89f4854c4ebb86f51 The ROM checksum 0x4F at 0x1FFF also seems correct. Loading "DTK ERSO...

Here's another Tava PC motherboard example. Appears to be the same MB from the chassis in post #1. Same part number "PART NO. 1001 REV B", stacked U82 and even has the yellow stickers on the CPU. I did not check the bodge wires matched but there are a few on this one. This one has a Tava V0.8...

To add just a bit more detail to Chuck(G)'s response. The eleven address bits are the concatenation of A0-A7 latched with ALE and three bits A8-A10 from port 2 bits 0-2.

I've got this MAXIT 256KB Memory Board but no manual. With four 8-bit DIP switches I'd rather not try shotgunning a configuration. If you have any info or insight on configuring this card I would appreciate it. Initially the plan was to use this card to backfill a 256KB PC, but having looked...

@Tom_Servo you did not indicate what size disk image you are trying to access on the gotek. Given you are using MS-DOS 1.0 and looking at the table sergey provided and looking at MS-DOS 1.0 disk limitation info from here it seems you need to be using a 160KB image. You would need to move to a...

Did you verify the EPROM contents on the programmer or read the EPROM from the card when installed in the PC? If the GAL logic of the defeatured card does not provide the correct chip select logic the EPROM can not be read. If you know the address where the EPROM is mapped then using the dump...

Maybe the GALs of the defeatured card do not provide select logic for the added components. This would be a simple way to thwart end user upgrades. You can use debug to dump/examine the cards EPROM to see if it's readable.

Checking this out has been on my list for a while. I've not been able to find much info on this particular device. Bitsavers provides info to identify the base unit as a Ungermann-Bass Network Storage Module (NSM) model 3121A NSM-1. Bottom of page 8...

The CPU-6A EPROM sockets are J75, J76, J77 and J78. The ones you reference are for components underneath the EPROMs. The EPROM Area 1 and 2 diagrams highlight the EPROM locations and designators. These are figures 4.1-2 and 4.2-1 of the document @djg pointed to in the first reply. The EPROM...

@tonata I have the same board and the ROMs are marked very similar to yours. Dumping the original ROMs it appears to be a custom PDOS application produced by or for Alphasem. I've been unable to find copies of the original VMEPROMs. If you find them I would like to get a copy. Good news...

Still working on the assumption that the drive electronics are good. I would agree with @Chuck(G) that this is looking like a mechanical issue. I came here to recommend that you try to wiggle the head positioning motor to see if it is loose. It seems you've been at this a while but have you...

Wow! It's even more impresive looking at the close up shots. Thanks for all the info on your tool flow. I'll be checking out FlatCAM and those bits. Jesse.

Nice and clean! What PCB mill did you use? I've got a T-Tech that I need to develop a KiCad tool flow for.