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Forum Index : Microcontroller and PC projects : MM Memory map
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| MOBI Guru  Joined: 02/12/2012 Location: AustraliaPosts: 819 |
Perhaps I've missed it somewhere in all the data I've downloaded about the Colour MM, but is there a memory map available for the MM? David M. |
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CircuitGizmos Guru Joined: 08/09/2011 Location: United StatesPosts: 1425 |
Things move around in memory, so there is no memory map. See the PEEK and POKE commands for offsets to the memory areas. Micromites and Maximites! - Beginning Maximite |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
The underlying pic32 has a memory map (actual and virtual)showing the location and size of the flash and RAM memories indicating the location of boot and SFR sections etc. Perhaps it is not relevant, but I was curious how much space the MMBasic, A-drive, video size and structure etc took. I used to have Microsoft Basic in ROM (8K) in the late 70's (Mostek 6502) around which I built a back plane based system for which I wrote the bios. I could also replace the 6502 board with say the Z80 to emulate e.g. the Trash80. Except for the 8k Basic, all the RAM and peripheral devices remained in place. All file i/o was done on a modified cassette player run at high speed, coupled directly to the R/W head. Anyway, I was just curious. David M. |
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| CircuitGizmos Guru Joined: 08/09/2011 Location: United StatesPosts: 1425 |
You hadn't asked for the PIC memory map. You asked for the MM memory map. The size and location of segments are dynamic. Size of video memory, for instance, depends on the video mode. I still have Z80 cassette routines written out long hand in assembly. Op code on the left, machine code painstakingly "compiled" by hand on the right. It is around here somewhere... Micromites and Maximites! - Beginning Maximite |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
Hi Gizmos, Thanks for that, as I said, it was idle curiosity. Also, I wouldn't mind a dollar for every page of hand written assembly code I've produced and for every 2708,16,32 uvROM I've erased and reprogrammed..I'd be retired a bit more comfortably than I am... Hope these colour MMs turn up soon, I'm really looking forward to having a bit of a play while the wife is away for a couple of weeks. What is the usual delivery time, any idea? David M. |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 3802 |
You can build (compile & link) MMBasic to get a MAP file. The main layout is controlled by a linker input file (procdefs.ld, Maximite.ld or similar). For the PIC32 itself, Microchip detail it in the datasheets. It's a bit more complicated than for 8-bit chips, especially if you remap the space as I believe retrobsd does. The ld file can be a bit daunting but bear in mind the linker supports lots of CPU families (x86, ARM, PIC, etc) and with generality comes some complexity. John |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
Thanks John, I guess I'll just have to wait until my MMs get here so I can stop asking questions and start doing. It was nice in the early days of MPUs where the memory map was a nice, easy to manage contiguous block of locations. I guess there was a sound hardware reason for MCUs to put blocks of RAM etc into banks. I have ordered some PIC32 795 chips as well to have a tinker with. Now I need to see if my PCB etching prowess can deal with so many close tracks. David M. |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 3802 |
It's all directly addressable by the CPU (*) - and by the DMA channels, too. Nowt wrong with asking questions, it's a big reason why TBS is here :) (= nothing) (*) in the way MMBasic uses it, but you can remap it if you wish John |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
It is not my intention to "re-map" anything. In the days of early PCs (and I suppose, modern PCs) there were I/O vectors and things that one could Peek and Poke in Basic and so allow data to go elsewhere or to use handy machine code subroutines in the built in Basic and Bios for other purposes. I just wondered if the same were possible in the MM. David M. |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 3802 |
Peek & Poke, yes. The loadable/callable lower-level (likely C nowadays), no. (Another job for someone to add it.) John |
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