Bah Humbug


Comments

Post a Comment

Popular posts from this blog

Slow Slow Slow

Image
Things slowed down a bit on the Build of my update, I need to improve my soldering skills and ability to order the right ICs. It would also be a lot better if I didn't throw away the FLASH chip with the old broken socket.  Just a single 74HCT08 to go.
Read more

Interrupted

Image
It has been a while. Full-time paid employment means I have enough cash to finish this but limits the time I can spend finishing it. The current state of play it that I have added some SMDs to get in some practice with those. One of the SMDs is a frequency multiplier so that with the original crystal to drive the video I can vary the CPU speed from the 3.278MHz of the original ACE up to 19.668MHz and perhaps beyond. I've also made some modifications to make the KIO optional and enable full ACE compatibility. The KIOs are very difficult to get hold of and with Z84C15 and Z182 available these seem like the best CPU to be going forward. The fastest CPU I have is 20MHz and while I had to up the speed of the RAM, everything else seem happy on the CPU side. The Video was less happy, but I am not 100% convinced that was a speed problem. The multiplier I'm using on this board is a Renesas 512MLF , which is pin compatible with the On Semiconductor NB3N502DR2G , though the multiplicat
Read more

Ace Board 3 EXP.

Image
The main thrust of my work at the moment it on ACE3NOKB   which includes some significant changes to use more modern components and fully populate the RAM as well as make some space for extra ROM. Included on the board is a Zilog KIO Z80C90 chip. This means that there will have to be a change in the interrupt structure which requires the extra ROM. It is all here but is ongoing work so less than 0 guarantees are provided. As you can see I've moved to PLCC for the Z80, which is the larger of the 2 brown sockets. The smaller socket contains NOR-Flash memory which will help in development by allowing me to update the firmware. The large empty socket is for the Zilog KIO this provides 2 serial channels, 24 GPIO pins and 3 CTC, one of which will handle the 50hz interrupt this will entail a move to interrupt mode 2 . To create space for the extra ROM I've moved the start of the system RAM up 1k so that the 4k between 12k and 16k can be used. The 2 chips next to the ROM socket a
Read more