diff --git a/src/include/86box/machine.h b/src/include/86box/machine.h
index 9cb155f81..1191d5100 100644
--- a/src/include/86box/machine.h
+++ b/src/include/86box/machine.h
@@ -54,7 +54,6 @@
 #define MACHINE_PCMCIA		0x00000400	/* sys is AT-compatible laptop with PCMCIA */
 #define MACHINE_AGP		0x00000A0C	/* sys is AT-compatible with AGP  */
 #define MACHINE_AGP98		0x00000A10	/* sys is NEC PC-98x1 series with AGP (did that even exist?) */
-#define MACHINE_IS_AT		0x00000FCC	/* sys is AT-compatible (ISA + ISA16) */
 /* Feature flags for miscellaneous internal devices. */
 #define MACHINE_VIDEO		0x00001000	/* sys has int video */
 #define MACHINE_VIDEO_ONLY	0x00002000	/* sys has fixed video */
@@ -83,7 +82,8 @@
 #define MACHINE_SCSI		0x08000000	/* sys has int single SCSI - mark as pri SCSI */
 #define MACHINE_SCSI_DUAL	0x18000000	/* sys has int dual SCSI - mark as both pri and sec SCSI */
 
-#define IS_ARCH(m, a)		(machines[(m)].flags & (a)) ? 1 : 0;
+#define IS_ARCH(m, a)		(machines[m].flags & (a)) ? 1 : 0;
+#define IS_AT(m)		((machines[m].flags & 0x00000FCC) && !(machines[m].flags & MACHINE_PC98)) ? 1 : 0;
 
 #define MACHINE_MULTIPLIER_FIXED -1, -1
 
@@ -492,8 +492,8 @@ extern int	machine_at_apas3_init(const machine_t *);
 extern int	machine_at_wcf681_init(const machine_t *);
 extern int	machine_at_6via85x_init(const machine_t *);
 extern int	machine_at_603tcf_init(const machine_t *);
-extern int  machine_at_trinity371_init(const machine_t *);
-extern int  machine_at_p6bap_init(const machine_t *);
+extern int	machine_at_trinity371_init(const machine_t *);
+extern int	machine_at_p6bap_init(const machine_t *);
 
 /* m_at_misc.c */
 extern int	machine_at_vpc2007_init(const machine_t *);
diff --git a/src/machine/machine.c b/src/machine/machine.c
index 4ff0993bd..19f821419 100644
--- a/src/machine/machine.c
+++ b/src/machine/machine.c
@@ -76,7 +76,7 @@ machine_init_ex(int m)
 	is_vpc = 0;
 
 	/* Set up the architecture flags. */
-	AT = IS_ARCH(machine, (MACHINE_BUS_ISA16 | MACHINE_BUS_MCA | MACHINE_BUS_PCMCIA));
+	AT = IS_AT(machine);
 	PCI = IS_ARCH(machine, MACHINE_BUS_PCI);
 
 	/* Reset the memory state. */
diff --git a/src/nvr.c b/src/nvr.c
index fb7c3dfb8..d949c78bc 100644
--- a/src/nvr.c
+++ b/src/nvr.c
@@ -147,7 +147,7 @@ onesec_timer(void *priv)
 
     if (++nvr->onesec_cnt >= 100) {
 	/* Update the internal clock. */
-	is_at = IS_ARCH(machine, (MACHINE_BUS_ISA16 | MACHINE_BUS_MCA | MACHINE_BUS_PCMCIA));
+	is_at = IS_AT(machine);
 	if (!is_at)
 		rtc_tick();
 
diff --git a/src/pic.c b/src/pic.c
index ad2efc67e..8b0727070 100644
--- a/src/pic.c
+++ b/src/pic.c
@@ -176,7 +176,7 @@ find_best_interrupt(pic_t *dev)
 
     dev->interrupt = (ret == -1) ? 7 : ret;
 
-    is_at = IS_ARCH(machine, (MACHINE_BUS_ISA16 | MACHINE_BUS_MCA | MACHINE_BUS_PCMCIA));
+    is_at = IS_AT(machine);
     if (is_at && (ret != -1) && (cpu_fast_off_flags & (1 << dev->interrupt)))
 	cpu_fast_off_count = cpu_fast_off_val + 1;
 
@@ -187,7 +187,7 @@ find_best_interrupt(pic_t *dev)
 void
 pic_update_pending(void)
 {
-    int is_at = IS_ARCH(machine, (MACHINE_BUS_ISA16 | MACHINE_BUS_MCA | MACHINE_BUS_PCMCIA));
+    int is_at = IS_AT(machine);
 
     if (is_at) {
 	pic2.int_pending = (find_best_interrupt(&pic2) != -1);
@@ -227,7 +227,7 @@ pic_callback(void *priv)
 void
 pic_reset()
 {
-    int is_at = IS_ARCH(machine, (MACHINE_BUS_ISA16 | MACHINE_BUS_MCA | MACHINE_BUS_PCMCIA));
+    int is_at = IS_AT(machine);
 
     memset(&pic, 0, sizeof(pic_t));
     memset(&pic2, 0, sizeof(pic_t));
@@ -493,7 +493,7 @@ picint_common(uint16_t num, int level, int set)
     int is_at;
     uint8_t b, slaves = 0;
 
-    is_at = IS_ARCH(machine, (MACHINE_BUS_ISA16 | MACHINE_BUS_MCA | MACHINE_BUS_PCMCIA));
+    is_at = IS_AT(machine);
 
     /* Make sure to ignore all slave IRQ's, and in case of AT+,
        translate IRQ 2 to IRQ 9. */
diff --git a/src/win/win_settings.c b/src/win/win_settings.c
index 1ca739b9d..ae674e328 100644
--- a/src/win/win_settings.c
+++ b/src/win/win_settings.c
@@ -783,7 +783,7 @@ win_settings_machine_recalc_machine(HWND hdlg)
     accel.nSec = 0;
     accel.nInc = machines[temp_machine].ram_granularity;
     SendMessage(h, UDM_SETACCEL, 1, (LPARAM)&accel);
-    is_at = IS_ARCH(temp_machine, (MACHINE_BUS_ISA16 | MACHINE_BUS_MCA | MACHINE_BUS_PCMCIA));
+    is_at = IS_AT(temp_machine);
     if (!is_at || (machines[temp_machine].ram_granularity >= 128)) {
 	SendMessage(h, UDM_SETPOS, 0, temp_mem_size);
 	h = GetDlgItem(hdlg, IDC_TEXT_MB);
@@ -990,7 +990,7 @@ win_settings_machine_proc(HWND hdlg, UINT message, WPARAM wParam, LPARAM lParam)
 			temp_mem_size = machines[temp_machine].min_ram;
 		else if (temp_mem_size > machines[temp_machine].max_ram)
 			temp_mem_size = machines[temp_machine].max_ram;
-		is_at = IS_ARCH(temp_machine, (MACHINE_BUS_ISA16 | MACHINE_BUS_MCA | MACHINE_BUS_PCMCIA));
+		is_at = IS_AT(temp_machine);
 		if (is_at && (machines[temp_machine].ram_granularity < 128))
 			temp_mem_size *= 1024;
 		free(stransi);
@@ -1609,7 +1609,7 @@ win_settings_peripherals_proc(HWND hdlg, UINT message, WPARAM wParam, LPARAM lPa
 
 		settings_enable_window(hdlg, IDC_COMBO_SCSI, d);
 		settings_enable_window(hdlg, IDC_CONFIGURE_SCSI, scsi_card_has_config(temp_scsi_card));
-		is_at = IS_ARCH(temp_machine, (MACHINE_BUS_ISA16 | MACHINE_BUS_MCA | MACHINE_BUS_PCMCIA));
+		is_at = IS_AT(temp_machine);
 		settings_enable_window(hdlg, IDC_CHECK_IDE_TER, is_at);
 		settings_enable_window(hdlg, IDC_BUTTON_IDE_TER, is_at && temp_ide_ter);
 		settings_enable_window(hdlg, IDC_CHECK_IDE_QUA, is_at);