69 RECLEN Number of bytes of data in this record &512
71
RECNAM Filename with trailing spaces
81
DESCHK
Checksum of the preceding 14 bytes
82
CHDATA
512 bytes of data
594
DCHK Checksum of the preceding 512 bytes
MAP
For every Microdrive containing an opened file there is an area called a MAP
created in the area called “Microdrive maps” in the BASIC programming
manual. The MAP contains 32 bytes. Each bit corresponds to a sector on the
corresponding Microdrive. If that sector contains data or if it is unusable then
the bit is ret. The bits are numbered as follows: bit 0 byte 0 = sector 0,
bit 1 byte 0 =sector 1, bit 0 byte 1 = sector 8. and so on.
Network channel
When a stream is opened to the network, a channel is created in the area
designated CHANS in the BASIC programming manual. This area is usually
addressed by the IX register in the software. The channel has a length of
276 bYtes, and contains the 255 byte buffer.
The contents of the channel are described as follows:
0
2
4
5
7
9
11
NCIRIS
12
NCSELF
13
NCNUMB
15
NCTYPE
16
NCOBL
17
NCDCS
18 NCHCS
19
NCCUR
20
NCIBL
21 NC6
Address 8
Address 8
“N”
Address of output subroutine in ROM
Address of input subroutine in ROM
Address 276
The destination station number
This SPECTRUM’s station number
The block number
The packet type code. .0 data, 1 EOF
Number of bytes in the data block
The data checksum
Theheaderchecksum
The position of the last character taken from the buffer
The number of bytes in the input buffer
A 255 byte data buffer
49
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