Three development versions of Samtrum are planned.
Samtrum 1 Will be simplest as possible.
Only 4MB RAM and socket for Z80CPU, at
6MHz and 3.5MHz, perhaps 8MHz if it will
work. Perhaps a YABUS slot.
Samtrum 1 will work as:
1. 4MB RAM extension (Sam has 4.5MB).
2. ZX128 hardware emulator (when the second
Z80CPU is inserted and enabled). 4MB RAM
Will have buffers and extra switching logic, so
more modes will be available:
3. Both the internal and the extra Z80 will be
able to work in the same time. The internal one
operates on internal 512kB RAM and internal
interfaces (keyboard, FDD, Atom), while the
external one on 4MB RAM and external interfaces
(Sambus, YABUS). To exchange data between them,
other mode must be selected (and one CPU
4. 512kB RAM of the 4MB RAM duplicates the
internal RAM and only external CPU works. The
internal RAM is only written by CPU (delayed if
necessary for faster clock - up to 21MHz due to
60ns DRAM access time). Sam has 4MB RAM, but can
work with very fast CPU.
Will have and support my new bus, that allows
to use CPU cards, graphics cards, DMA cards and
configuration cards. New modes:
5. Without CPU card, Sam can work with graphics
cards and some DMA cards.
6. With CPU card (I mean here eZ80) Sam hardware
is used as graphics and I/O card. Samtrum 3 offers
default "Sam compatibility" configuration, but with
an extra configuration card its structure can be
converted to almost any hardware compatibility
(e.g. ZS Scorpion, ZX Spectrum +3).
- Using Sam with 4.5MB RAM
- Hardware emulation of ZX Spectrum 128kB.
- Hardware emulation of Pentagon 512kB.
- Using Z80 up to 16MHz.
- Using Z88 software.
- 4MB 60ns DRAM
- Z80 with own programmable clock and WAIT control.
- YABUS slots.
- Up to 512kB Flash EPROM (not sure).
- Memory switched using #D0..#D3 ports, as in Z88.
- Alternate memory switchind in ports #80, #81 (Sam).
- Alternate memory switching with port #7FFD (ZX128).
- ZX128 emulation supported in ZXVGS.
Links to other pages
- Sam Coupé
- The Sam Coupé computer by MGT.
- Dinamic Random Access Memory (DRAM). Memory with multiplexed address lines.
- 4MB RAM upgrade : ZX Spectrum
- ZX Spectrum memory upgrade - 4MB RAM (DRAM).