Samtrum

Three development versions of Samtrum are planned.

Samtrum 1

1. 4MB RAM extension (Sam has 4.5MB).

2. ZX128 hardware emulator (when the second Z80CPU is inserted and enabled). 4MB RAM is available.

Samtrum 2

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 disabled).

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.

Samtrum 3

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).

Purposes

• 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.

Properties

• 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.

Linki do innych stron

Zobacz również

Sam Coupé

Komputer Sam Coupé firmy MGT

DRAM

Pamięć dynamiczna o dostępie swobodnym (DRAM). Multipleksowane linie adresowe.

4MB RAM upgrade : ZX Spectrum

Rozszerzenie pamięci dla ZX Spectrum - 4MB RAM (DRAM).