*** M E M O R U M ***

Steve, Thanks for the feedback. I must admit I never found the time to go back and look at my Windows installation. With regard to hosting on GitHub, my theory was that when I got bug reports it would be easier for me to just push updates to a repository, rather than having to create a new zip file ...

The only thing which probably needs addressing is the storage. Being limited to the original SD card specification is a headache as hardly any small SD cards exist. Also having it as raw storage limits things. Maybe a future upgrade could be to encapsulate the drive image into a file on a FAT files...

And when doing the address decode on a microprocessor where each comparison requires a couple of instructions (a test and a jump) the additional time needed for the odd addresses is a pain. I certainly cursed the decision while writing the Propeller code for the CFX-II.

Anyway, it is inelegant

I suppose the VDP addressing only really becomes a pain when you try and make video add-ons. Whether working in hardware, on a FPGA or a microprocessor you often need a signal to say this is a VDP address. If the VDP was on addresses 0x02 and 0x03 then this signal would be: VDP = A1 & /A2 & ...

Why did Memotech have to put the VDP on Z80 ports 0x01 and 0x02? It makes decoding VDP addressing more difficult. It would be easier if the VDP was either on 0x00 & 0x01 or on 0x02 & 0x03. In general it is easiest if common functionalities have the same high bits in the port address and all ...

Steve, Thanks for the feedback. Spaces in a path name are a pain, need to make sure there are double quotes in all the right places. I will have to check where I installed SDCC on my Windows 10 PC. Like you I normally avoid C, however since I was trying to make everything easy to use I probably acce...

Does the attached help?

The CTC (like most Z80 peripherals) is really only designed to work with mode 2 interrupts. Something like: ctc0 equ 0x08 cfgctc: di im 2 ld a, #0xC5 out (ctc0), a ; Counter mode, interrupt, time constant follows. ld a, #1 out (ctc0), a ; Interrupt on every VDP pulse ld hl, #ijtbl ld a, l out (ctc0)...

Interrupts from VDP or CTC? Have you set the interrupt enable bit on the VDP if that is what you are using? Have you configured the CTC to generate an interrupt, either on a pulse from the VDP, or on a time elapsed? Which interrupt mode is the Z80 in? What is the I register set to? What interrupt ve...

I have started a new thread with the latest version.