Dear members,
I wrote a program for AT89S52 in assembler with MED-editor and I produce HEX-code with cross-assembler XMCS51, to program the flash I use AEC_ISP.exe, I connected MOSI, MISO and others direct (with 300-ohm resistors in serie). It works fine
-- but

1. if my program contains more than 1K program-code the program AEC_ISP says it is NOT possible – why?
2. I read, that it is possible to program single bytes in flash-memory– how can I do so

I would be glad if I see any helpful answer.
With friendly regards
Manfred POMUTZ


AT89S52 8-bit Microcontroller
with 8K Bytes In-System Programmable Flash
1919B–MICRO–11/03
Features
• Compatible with MCS-51® Products
• 8K Bytes of In-System Programmable (ISP) Flash Memory
– Endurance: 1000 Write/Erase Cycles
• 4.0V to 5.5V Operating Range
• Fully Static Operation: 0 Hz to 33 MHz
• Three-level Program Memory Lock
• 256 x 8-bit Internal RAM
• 32 Programmable I/O Lines
• Three 16-bit Timer/Counters
• Eight Interrupt Sources
• Full Duplex UART Serial Channel
• Low-power Idle and Power-down Modes
• Interrupt Recovery from Power-down Mode
• Watchdog Timer
• Dual Data Pointer
• Power-off Flag
• Fast Programming Time
• Flexible ISP Programming (Byte and Page Mode)