Chinese 8088-based laptop system with pirated 8088 BIOS

[ImanolBarba]

If anyone is curious, I managed to dump the BIOS that it comes with.

This from the second batch of the product that was made available on Aliexpress. There is now another model with a couple more ports, so maybe that has a different BIOS entirely

 

[dhau]

It was very tempting to buy it, but I feel like I dodged the bullet. Based on MartyPC blog, it can't do DMA, pins are not connected. It's worse to have something defective than not have it at all.

 

[sergey]

If anyone is curious, I managed to dump the BIOS that it comes with.

This from the second batch of the product that was made available on Aliexpress. There is now another model with a couple more ports, so maybe that has a different BIOS entirely

• Still based on my BIOS, with even more text strings removed... Quite an original way to address my license/copyright complains
• Still ten years old Universal XT IDE BIOS, with all the bugs and sluggish performance

 

[Chuck(G)]

It's been going on for years, Sergey. Some 20 or so years ago, someone reported seeing my software tools with text strings modified(!) from a Korean CNC PLC maker. I confronted them and settled to give them a license (with text intact) and a one-time cash payment. They later came back to me for work on another product, so it was a win-win in spite of everything.

 

[Eudimorphodon]

Still based on my BIOS, with even more text strings removed... Quite an original way to address my license/copyright complains

That's certainly aggrieving, and pointlessly self-defeating considering you've officially incorporated support for their sketchy product into the upstream repository. It's like whoever is churning this out is so used to an environment where you *have* to hack source ROM images to give Mario a green hat and change the title screen to "Superfluous Pipe Friends" to avoid (ultimately mostly impotent) attempts by the copyright holder to ban-hammer their product that they just can't grok the concept of giving credit where credit is due.

 

[GloriousCow]

It was very tempting to buy it, but I feel like I dodged the bullet. Based on MartyPC blog, it can't do DMA, pins are not connected. It's worse to have something defective than not have it at all.

Can't do DMA for DRAM refresh - and they bungled up DMA channel #1, but channels #2 and #3 in theory should work off the ISA port. I haven't tested it though as I don't have the little ISA expansion unit.

 

[ImanolBarba]

Maybe a dumb question, but I am only learning about general PC XT at this level now: is the DMA channel #1 used for anything else besides DRAM refresh in the original XT?
Where I'm getting at is, besides the timing inaccuracies due to the extra cycles otherwise stolen by the DRAM refresh, is there any other potential incompatibilities? Would any other software attempt to reuse that channel for some other purpose? I don't think so but maybe I just don't know enough about this

Thanks!

 

[ImanolBarba]

Also another question about reading your blog post (btw very nice read!), you mentioned that:

> Even more puzzling is DACK1 is tied to ground, but DREQ1 is not.

I found this somewhat concerning so to make sure I checked the schematic an it seems that it runs to the ISA port as well. I also did a continuity test on the PCB and it does not appear that DACK1 is tied to ground.

How did you come to this conclusion? is there something I missed?

 

[GloriousCow]

Maybe a dumb question, but I am only learning about general PC XT at this level now: is the DMA channel #1 used for anything else besides DRAM refresh in the original XT?
Where I'm getting at is, besides the timing inaccuracies due to the extra cycles otherwise stolen by the DRAM refresh, is there any other potential incompatibilities? Would any other software attempt to reuse that channel for some other purpose? I don't think so but maybe I just don't know enough about this

Thanks!

DMA channel #0 is used for DRAM refresh. On a typical PC/XT system, DMA channel #2 would be used by the floppy controller and DMA channel #3 by the hard disk controller, although I suppose this was configurable depending on the controller. This left you with one usable DMA channel, #1, for an expansion card, so you could add a Soundblaster or something equally anachronistic. The paucity of DMA channels was addressed on the AT by adding a second DMA controller.

Since the XT-IDE in the Book8088 doesn't use DMA it makes up for the miswired DMA channel #1, so I guess you're no worse off.

 

[GloriousCow]

Also another question about reading your blog post (btw very nice read!), you mentioned that:

> Even more puzzling is DACK1 is tied to ground, but DREQ1 is not.

I found this somewhat concerning so to make sure I checked the schematic an it seems that it runs to the ISA port as well. I also did a continuity test on the PCB and it does not appear that DACK1 is tied to ground.

How did you come to this conclusion? is there something I missed?

it would have been a continuity checker as well, maybe there's just an issue with mine, or I just messed up there. i have been known to be wrong on occasion :D i'll double-check next time I have it apart.


In other news, my bus sniffer is almost done; i've made it somewhat modular to be able to swap it between my 5150 and the Book8088; should be interesting to see if there's any differences that crop up while running Area 5150.

I'm probably chalking it up to CGA emulation issues, but if there's something correctable, would be fun to get over the last hurdle.

In a worst case scenario, does anyone know if its possible to reprogram the CPLDs?

 

[sergey]

In a worst case scenario, does anyone know if its possible to reprogram the CPLDs?

It is possible to reprogram...
The problem is that it might not be possible to read (might have security / read protect feature enabled).
Also, I don't think the CPLD source code, VHDL or whatever they've used, wasn't publicly released.
It might be possible to write your own code, but that would require quite a bit of effort.

 

[ImanolBarba]

it would have been a continuity checker as well, maybe there's just an issue with mine, or I just messed up there. i have been known to be wrong on occasion :D i'll double-check next time I have it apart.


In other news, my bus sniffer is almost done; i've made it somewhat modular to be able to swap it between my 5150 and the Book8088; should be interesting to see if there's any differences that crop up while running Area 5150.

I'm probably chalking it up to CGA emulation issues, but if there's something correctable, would be fun to get over the last hurdle.

In a worst case scenario, does anyone know if its possible to reprogram the CPLDs?

I double checked and I get continuity from DACK1 to the ISA port in the back where DACK1 is supposed to be.

My board is revision 1.7.1, maybe they realised the mistake and fixed it?