Intel mcs-48 SA Programming Module Cross Reference Module Name USE with, Upp, UPPI41, UPP UP2121

8755A

ERASURE CHARACTERISTICS

The erasure characteristics of the 8755A are such that erasure begins to occur when exposed to light with wavelengths shorter than approximately 4000 Angstroms (AI. It should be noted that sunlight and certain types of fluorescent lamps have wavelengths in the 3000-4000A range. Data show that constant exposure to room level fluorescent lighting could erase the typical 8755A in approximately 3 years while it would take approxill1ately 1 week to cause erasure when exposed to direct sunlight. If the 8755A is to be exposed to these types of lighting conditions for extended periods of time, opaque labels are available from Intel which should be placed over the 8755 window to prevent unintentional erasure.

The recommended erasure procedure for the 8755A is exposure to shortwave ultraviolet light which has a wave- length of 2537 Angstroms (AI. The integrated dose Ii.e., UV intensity X exposure time) for erasure should be a minimum of 15W-sec/cm2. The erasure time with this dosage is approximately 15 to 20 minutes using an ultra- violet lamp with a 12000",W/cm2 power rating. The 8755A should be placed within one inch from the lamp tubes during erasure. Some lamps have a filter on their tubes and this filter should be removed before erasure.

SYSTEM APPLICATIONS

System Interface with SOSSA

A system using the 8755A can use either one of the two I/O Interface techniques:

•Standard I/O

•Memory Mapped I/O

If a standard I/O technique is used, the system can use the feature of both GE2 and CE1. By using a combination of unused address lines A11-15 and the Chip Enable inputs, the 8085A system can use up to 5 each 8755A'swithout requiring a CE decoder.

If a memory mapped I/O approach is used the 8755A will be selected by the combination of both the Chip Enables and 10/M using the AD8-15 address lines. See Figure 1.

PROGRAMMING

Initially, and after each erasure, all bits of the EPROM portions of the 8755A are in the "1" state. Information is introduced by selectively programming "0" into the desired bit locations. A programmed "0" can only be changed to a "1" by UV erasure.

The 8755A can be programmed on the Intel® Universal PROM Programmer (UPPI, and the PROMPT'"80/85 and PROMPT-48'"design aids. The appropriate programming modules and adapters for use in programming both 8755A'sand 8755'sare shown in Table 1.

The program mode itself consists of programming a single address at a time, giving a Single 50 msec pulse for every address. Generally, it is desirable to have a verify cycle after a program cycle for the same address as shown in the attached timing diagram. In the verify cycle (i.e., normal memory read cycle I 'Voo'should be at +5V.

Preliminary timing diagrams and parameter values per· taining to the 8755A programming operation are con· tained in Figure 6.

TABLE 1. 875SA PROGRAMMING MODULE CROSS REFERENCE

MODULE NAME USE WITH

UPP 955	UPPI41
UPP UP2121	UPP 855
PROMPT 975	PROMPT 80/85131
PROMPT 475	PROMPT 48( 11

NOTES:

1, Described on p. 11·9of 1978 System Data Catalog.

2.Special adaptor socket.

3.Described on p. 11·3of 1978 System Data Catalog.

4.Described on p. 10·85of 1978 System Data Catalog.

	/1			"
	1~8-15			~
BOB5A	MOo.7
				V
	RO	-
	"ALE
	WR	;---
		r--
	elK 102)
		r--
	REAOY
		r--
	Vee			*1
		;---
	101M
	rV '\..7			I
	iifR	AID,., A'_10	RD	elK 101M
			ALE ilii'i READY CE
			B755A

'NOTE:Optional connection.

Figure 1. 8755A in 808SA System (Memory-Mapped 1/0)

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