Info about Compaq Portable 1

[cognitivegears]

Thank you so much for creating this repo and archiving this information!

I wanted to confirm that the PC-Sprint does work on the Compaq Portable 1 as well. A couple of notes on it:

• The 8284A on the Compaq Portable 1 is unfortunately soldered onto the motherboard, so a socket needs to be installed prior to using a PC-Sprint
• Due to the placement of the 8284A near the edge of the motherboard, when installed the original 5 1/4 inch drive in the first slot will overlap and not give room for the installation. In my case since I only had one 5 1/4 inch drive I moved it to the other bay.
• You will most likely need to install the PC-Sprint after installing the motherboard in the case due to the limited space. It is possible to reach the 8284A with the motherboard installed as long as the ISA cards are removed.
• I only tried a 21.47 mhz crystal so far but everything has been stable. Other cards include the original floppy controller card, original CGA card, an ISA CF card adapter and a SixPackPlus RAM Clock I/O board. The SixPackPlus does have some 200ns ram in one of the banks, but still seems to operate okay. The rest of the ram in the system is 150ns.
• I used a V20 D70108C-8 for the processor.
• My Compaq has a 8087-1 and worked without issues.

Other notes:

• You may want to mention that for the headers you need to get round pin headers that fit into DIP sockets - the regular rectangular pins for breadboards etc won't fit.
• I'm not sure if you are good with commercial links, but I used this link PCBWay. I'm not associated in any way, just worked well for me.

[reeshub]

Thanks so much for the detailed information! So great to hear that this also works well with the Compaq Portable 1. I'll try to get the page updated as soon as I can.

No problem at all with recommendations for professional services, I also used PCBWay to manufacture my boards and they were great. I've also had good experiences with JLCPCB - due to the simplicity of the board I should think that any commercial PCB fab can handle it just fine.

Interesting to hear about the 200ns RAM in the SixPakPlus, that's also very useful to know.

[cognitivegears]

A couple of pictures from the Compaq as well:

My build of the PC-Sprint:

Replaced 8284A with a socket:

[AtomicLunchbox]

Just wanted to add a couple of notes. I built one of these too for my Compaq Portable I

1) I don't think @cognitivegears has an original disk drive in his machine. The Compaq Portable used full height drives and the PC sprint blocks both bays. I've been looking for a solution to relocate it but haven't found a readily available ribbon cable/socket. A slight modification to the board layout might make the first bay (nearest to the monitor) accessible. 2) My configuration is similar: V20 + 8087-1, oem cga/mda card, oem floppy controller, AST MegaPak II (RAM + Clock) and XT-CF card 3) I've only tried a 22.11MHz crystal and everything was stable at the faster speed with the exception of the disk drive which seemed flaky. I didn't narrow that down to the controller or the drive itself.

If I come up with a good way to install the PCB and use the disk drive, I'll follow up.

[cognitivegears]

Thanks @AtomicLunchbox - I have one original drive, though without the original cage. For the other one I was missing the original drive, so I made a 3d printed enclosure that has a gotek, as well as now a reset button and turbo button (connected to the PC-Sprint.) You can see the purple housing in one of the pictures that I posted.

I'm not sure how it could block both bays, but the closest bay I could definitely see it blocking without a replacement like I'm using.

[AtomicLunchbox]

@cognitivegears take look at the pictures above. Full height floppy (original) prevents the pc-sprint from being installed. There just isn't enough room. Your drive is a lot shorter than mine so I was assuming it's half height.

[Maillouski]

Hi gang! I am currently testing the pc-sprint on my Compaq board revision 1. I tried a 24mhz crystal and it fails with a RAM error 0002 201.

I know it is probably because it is too fast. what DRAM chip do you all have to be able to run it using a 22mhz crystal? Are the stock ram chips fast enough?

I do have a V20 but no math-co.

[AtomicLunchbox]

Mine is a Portable Plus, but it has the revision 1 board. The DRAM appears to be stock 200ns chips soldered on and 250 in the socketed banks. I also have an ISA RAM card with another 256K of 250ns parts.

[MicrowaveableTupperware]

Has anyone tried the Skinny Sprint V2 by Epictronics? It’s smaller and may fit under the floppy drive

https://github.com/epictronics/Skinny-Sprint/tree/main