Recent content by MicroCoreLabs

As a sanity check can you remove the ISA cards for floppy, HD, and XTIDE? The MCLV20_Max should be able to boot from the MicroSD. You said it went straight to basic, but did it first try to boot from sd? Are you sure the MicroSD is bootable? I suggest preparing the MicroSD with DOS 6.22...

Interesting. I wonder if their expansion rom addresses conflict. Can you try changing the xtide address? The BootRom base address can be changed in the header file. @mbucchia Can you boot from MicroSD if xtide is removed?

Would there be much interest in a minimum-mode version of the MCL86+ for use in the PCjr? It doesn't seem like a lot of work to adapt the design... Features that might be interesting: - Massive acceleration which is always fun - The full 640 KB emulated in the Teensy - MicroSD card access...

True. An in-depth debugger could be developed on this platform.

I picked up a IBM 5150 motherboard from the Silicon Valley Electronics Flea Market a a few weekends ago which appeared to be in very good condition. I powered it up with just the power supply, VGA card, and the speaker to see if it could POST, but unfortunately it could not. Well, I did hear...

I thought of implementing a similar project for an ISA bus card using an FPGA to integrate some of the features you described. I figure it could use a sub $5 FPGA, a few buffers and connectors, and the PCB. The XT_IDE-CF is very popular but there is no inexpensive equivalent yet for MicroSD.

Can a PCB edge be plugged directly to the 5140? If so, then you dont necessarily need to use that expansion form factor with its rare connectors. Just plug the new board directly to the 5140's motherboard - an enclosure could fabricated at some point if desired. You would lose the ability to...

Please note that the MCLV20_Max BootRom will boot from the MicroSD after the floppy then the physical hard disk. I wonder how it will interact with an XT_IDE - which will boot first and which BIOS will assume control. @Hasekura I also wonder how the speed of the MCLV20_Max MicroSD access...

In theory I could debounce the acceleration mode whenever the first address of the BootRom is accessed which should, in theory, only ever happen during warm and cold boots.

The new code is uploaded to GitHub: MCLV20_Max This code contains the XTMax BootROM which allows the MCLV20_Max to boot from the MicroSD. Please use the updated XTSD.SYS driver and dont forget to include the bootrom.h file in your Arduino project.

With @mbucchia 's help I was able to port his BootROM code from the XTMax to the MCLV20_Max to allow booting from the MicroSD. I need to remove debug messages and clean it up then I should be able to upload it tomorrow.

Yeah, I thought about this... I was wondering if I could monitor DMA-related accesses and perform reads/writes immediately before or after the DMA to maintain coherence between motherboard and mirrored RAM. Im not up to speed on how DMA is setup and kicked off, but I believe the CPU always...

Ah.. if the sound card uses DMA then yes, it won't work under ACC2 when all of the conventional RAM is inside of the Teensy.

I wonder if there is an address conflict between the MCLV20_Max EMS and your sound card. Do you know what I/O and memory addresses it responds to? EMS can be relocated if you need to.

I'm happy to see that you are getting such great results! Yes, there is no support for UMB at this time - Right now I am working on the BootROM so you can boot from the MicroSD instead of using the DOS driver. I had a breakthrough last night so hopefully it will be done soon. Please note than...