Tandy 1000 Technical Reference Manual

Tandy 1000 Technical Reference Manual
256K MEMORY EXPANSION JUMPER
OPTIONS AND CONFIGURATIONS
Memory Jumper Options
Listed below are the jumper options necessary for the correct operation of the
Tandy 1000:
1. With E1-E2 jumper installed, memory on board will be 256K in size, without
a jumper
at this location, memory will be 128K.
2. With E3-E4 jumpered, no DMA is present and the memory starting address
is 40000 hex. Without a jumper at this location, DMA is present and the
memory starting address
is 00000 hex.
If jumper E3-E4
is present, U13 (DMA) MUST NOT BE INSTALLED.
The first memory board MUST have DMA (U113) installed regardless whether
128K or 256K of memory
is present.
With two boards installed, the first memory board must be 256K.
See the chart
below:
E1-E2 E3-E4
Jumper in
Jumper out
NO DMA
256K MEM BASE ADDRESS 40000
DMA PRESENT
128K MEM BASE ADDRESS 00000
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Tandy 1000 Specifications

General

Processor	Intel 8088
Processor Speed	4.77 MHz
RAM	128 KB (expandable to 640 KB)
Operating System	MS-DOS 2.11
Manufacturer	Tandy Corporation
Release Year	1984
Storage	Single or double 5.25" floppy disk drive (360 KB), optional hard drive
Sound	Tandy 3-voice sound
Ports	Parallel, Serial
Graphics	CGA (Color Graphics Adapter)
Graphics Modes	320x200, 640x200