Data I/O UniSite-xpi, User Manual

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6. Translation Formats
UniSite-xpi User Manual 6-21
RCA Cosmac Format, Code 70
Data in this format begin with a start record consisting of the start
character (!M or ?M), an address field, and a space. See Figure 6-7.
The start character ?M is sent to the programmer by a development
system, followed by the starting address and a data stream which
conforms to the data input format described in the ASCII-Hex and Octal
figure. Transmission stops when the specified number of bytes has been
transmitted.
Address specification is required for only the first data byte in the
transfer. An address must have 1 to 4 hex characters and must be
followed by a space. The programmer records the next hexadecimal
character after the space as the start of the first data byte. (A carriage
return must follow the space if the start code ?M is used.) Succeeding
bytes are recorded sequentially.
Each data record is followed by a comma if the next record is not
preceded by an address, or by a semicolon if it starts with an address.
Records consist of data bytes expressed as 2 hexadecimal characters and
followed by either a comma or semicolon, and a carriage return. The
programmer ignores any characters received between a comma or
semicolon and a carriage return.
The carriage return character is significant to this format because it can
signal either the continuation or the end of data flow; if the carriage
return is preceded by a comma or semicolon, more data must follow; the
absence of a comma or semicolon before the carriage return indicates the
end of transmission.
Output data records are followed by either a comma or a semicolon and a
carriage return. The start-of-file records are expressed exactly as for
input.
Figure 6-7
An Example of RCA Cosmac
Format
!M0000 ,
FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF,
FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF,
FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF,
FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF,
FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
Start Record
!M or ?M = Start Characters
0000 = Address
End-of-File Record
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2
Data Records
FF =
, =
; =
2 Hex Characters = (1 Byte)
Bytes per record is variable
End of Record Character
End of Record Character
if followed by expressed
address
LEGEND
Nonprinting line feed, carriage return, and nulls
Nonprinting carriage return
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