MicroCoreLabs
Experienced Member
- Joined
- Feb 12, 2016
- Messages
- 285
I was thinking of making a small board which could replace the 8088 on the PCjr and wanted to see if there was any interest...
Basically it would contain an FPGA running the MCL86 CPU core which could be set to cycle accurate mode or set to "unlocked" which runs much faster. A 512KB SRAM chip would bring the total memory to 640KB and could run at the 100Mhz core's speed.
This would be an integration of a project I did a few years ago... See links below...
To spice things up, a second 128KB SRAM could be added in the address range of the two PCjr cartridges, so we could upload the images to the SRAM via diskette/JrIDE, then after resetting the machine, it would wake up with the cartridge(s) installed...
In theory, the PCjr's BIOS could also held in SRAM... So after first boot we could upload the new BIOS to SRAM and have the FPGA boot from this alternate image after reset... for those who dream of rolling their own PCjr BIOS!
Anyway, I had fun with this project as a prototype... The FPGA held 128KB of the PCjr's RAM, and was cycle "unlocked", so it yielded a PCjr which was faster than a PCAT!
Thoughts/ideas?
Thanks,
-Ted
https://microcorelabs.wordpress.com/2017/01/02/worlds-fastest-pcjr/
https://microcorelabs.wordpress.com/2017/01/01/ibm-pcjr-running-the-mcl86-with-minimum-more-biu/
Basically it would contain an FPGA running the MCL86 CPU core which could be set to cycle accurate mode or set to "unlocked" which runs much faster. A 512KB SRAM chip would bring the total memory to 640KB and could run at the 100Mhz core's speed.
This would be an integration of a project I did a few years ago... See links below...
To spice things up, a second 128KB SRAM could be added in the address range of the two PCjr cartridges, so we could upload the images to the SRAM via diskette/JrIDE, then after resetting the machine, it would wake up with the cartridge(s) installed...
In theory, the PCjr's BIOS could also held in SRAM... So after first boot we could upload the new BIOS to SRAM and have the FPGA boot from this alternate image after reset... for those who dream of rolling their own PCjr BIOS!
Anyway, I had fun with this project as a prototype... The FPGA held 128KB of the PCjr's RAM, and was cycle "unlocked", so it yielded a PCjr which was faster than a PCAT!
Thoughts/ideas?
Thanks,
-Ted
https://microcorelabs.wordpress.com/2017/01/02/worlds-fastest-pcjr/
https://microcorelabs.wordpress.com/2017/01/01/ibm-pcjr-running-the-mcl86-with-minimum-more-biu/