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JANUS? 2020 Hand-Held Computer (4MB) - Intermec

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Types of Memory Used in the Reader<br />

Memory Map<br />

NF BC Reader Specifications<br />

A<br />

The <strong>JANUS</strong> reader uses the types of memory described in this section. Memory<br />

in the reader is similar to that of a PC in some ways, and very different in other<br />

ways. One major difference is that the reader uses memory to simulate disk<br />

drives. This memory map shows how the reader uses memory.<br />

Address Contents Description<br />

FFFFFF<br />

E00000<br />

C00000<br />

880000<br />

800000<br />

400000<br />

110000<br />

100000<br />

FFFFF<br />

FFFF0<br />

F2000<br />

F0000<br />

E0000<br />

D0000<br />

C0000<br />

No Physical Memory End of 386SX Address Space<br />

APPLICATION DISK<br />

Drive D<br />

Unused Address Space<br />

No Physical Memory<br />

USER FLASH<br />

Drive C<br />

2MB Flash<br />

(3.5MB)<br />

512K Flash<br />

No Physical Memory (<strong>4MB</strong>)<br />

3MB DRAM<br />

Extended Memory<br />

Contains 256K Drive E:<br />

HIMEM, 64K<br />

MS-DOS 6.2 Loaded<br />

RESET VECTOR<br />

(10H Bytes)<br />

BIOS & PM<br />

(56K)<br />

INT13/19<br />

(4K, 8K allowed)<br />

BIOS Extensions<br />

(64K)<br />

Scanner/Decodes<br />

(64K)<br />

PC Card Window<br />

(64K)<br />

HIMEM is included in this 3MB<br />

1MB Real Mode Boundary<br />

Bootstrap Vector<br />

10H ASIC BANKED<br />

BIOS Flash, Shadowed<br />

BIOS Extensions, Shadowed<br />

Upper memory block<br />

Can be used for optional upper memory<br />

A-15

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